Hello.
I'm Nadjib, a Professional .NET/Xamarin developer (12+ years experience). I can create your prices comparator and expense tracker Android app with ease. I can also contribute to this project by giving (my humble) advices and orientations.
I use latest programming technics (MVVM, IoC...) and my code is clean and easily maintainable/extensible. I also work with Scrum (Agile) technic + Git.
I hope we'll collaborate on this project, I'm sure you'll be fully satisfied. My skype's nadjib213, feel free to add me and ask me questions if you have any (or you can just say hi!)
PS: I also can create the WP8+ version of the app if you want.
Best regards,
Nadjib Bait.